Ocular and biochemical abnormalities in gyrate atrophy of the choroid and retina.

Patients with gyrate atrophy of the choroid and retina have myopia, constricted visual fields, elevated dark adaptation thresholds, small or nondetectable ERGs, and chorioretinal atrophy. Biochemical abnormalities include hyperornithinemia, hypolysinemia, hyperornithinuria, an unknown amino compound in the urine, and virtual absence of OKT activity in extracts of cultured skin fibroblasts. Extracts of cultured skin fibroblasts from one patient studied in our laboratory showed an increase in OKT activity with increasing concentrations of vitamin B6 in the assay medium; this patient also showed some biochemical responsiveness within three weeks to 300 mg/day or orally administered vitamin B6. Three patients whose fibroblasts did not show increased OKT activity in vitro with increasing vitamin B6 did not respond in vivo to 300 mg/day of vitamin B6 over the same period. All four patients continue to be evaluated with larger doses of this vitamin. It remains to be established if long-term treatment with vitamin B6 will stabilize the course of the chorioretinal degeneration for at least some patients with this disease.